How Often Should You Add Chlorine to Your Pool?

Written by Michael Dean
November 28, 2023

chlorine dispenser and calendar

Any pool owner knows that chlorine is the key ingredient to keeping your swimming pool clean and healthy. But if you’re new to pool maintenance, you might wonder: Exactly how often should you add chlorine to your pool?

In this article, I will answer the above question, break it down by chlorine type, and answer other frequently asked questions regarding pool chlorine. Let’s dive in.

Main Takeaways 

  • Add chlorine as often as needed to maintain levels of 1 to 3 ppm, which is anywhere between every day to once a week, depending on the type of chlorine.
  • How often you add chlorine will depend on factors such as the type of chlorine and sunlight.
  • You can lower too-high chlorine levels with several methods, including using the sun, diluting the water, and using a chlorine neutralizer.
  • Maintain the chlorine levels of your pool by testing regularly, shocking the pool, and running the pool pump, among other tips.

How Often Should You Add Chlorine to Your Pool?

There is no one-size-fits-all answer for how often you should add chlorine to your pool. But as a general rule, I recommend adding chlorine as often as needed to maintain chlorine levels between 1 and 3 ppm. For many pool owners, this means adding chlorine to the pool every day or every second day. However, this isn’t always the case.

Here are some additional factors that may cause you to add chlorine to your pool more or less often.

Type of Chlorine

I’ll dive into this a bit deeper below, but the type of chlorine impacts how often you add chlorine to the pool. Notably, tablets, such as trichlor, don’t need to be added as often. This is because you’ll put trichlor in a floating or automatic chlorinator, which dispenses chlorine slowly into your pool to maintain the correct chlorine levels. In this case, you may not even have to add chlorine very often, as you’ll just top up the dispenser when it gets low.

Unusual Circumstances

You’ll need to add chlorine to your pool in the following circumstances:

In some cases, these situations may even require you to shock the pool to get the chlorine levels back in check.


Sunlight affects the chlorine levels in your pool. While you may enjoy the warm sun, the harsh UV rays actually break down chlorine. To counteract this, use cyanuric acid to stabilize the chlorine. CYA acts like a sunscreen for your chlorine. For this reason, depending on the amount of sun you get and your CYA levels, you may need to top up your chlorine more or less often than usual.

Winter Maintenance

During the off-season, when the swimming pool is not in use, you’ll cut down on the frequency of adding chlorine. However, you should still monitor the water periodically to prevent algae growth and keep the water properly balanced.

Remember: The best way to know when it’s time to top off your chlorine levels is to regularly test the pool water.

Types of Pool Chlorine

As I mentioned above, the type of chlorine you use can have some influence on how often you add chlorine to your pool.

Calcium Hypochlorite

Cal hypo stands for calcium hypochlorite and is a granular form of chlorine that dissolves rapidly. Generally, cal hypo is used as a pool shock, so you should use it just once a week – or once every two weeks if you switch off with non-chlorine shock. You may need to shock your pool more often after a pool party or a rainstorm and after noticing algae growth.

Lithium Hypochlorite

Lithium hypochlorite is probably one of the least popular types of chlorine to use in pools. While it is great for fiberglass or vinyl liner pools, it is more expensive. A granular chlorine, lithium hypochlorite is relatively fast-dissolving. As it’s unstabilized, make sure to add cyanuric acid to ensure the chlorine doesn’t immediately dissipate under the sun. As long as you add cyanuric acid, you should get away with topping up your chlorine every 1 to 2 days.

Sodium Hypochlorite (Liquid Chlorine)

Liquid chlorine, also called sodium hypochlorite or bleach, is one of the most common chlorine types used by pool owners. It is not only economical but also super easy and safe to use. As a general rule, I recommend adding liquid chlorine to your pool every 1 to 2 days. Test your chlorine levels daily to ensure you know when you need to top it up.


Trichlor is a super potent form of chlorine usually found in tablet form. This is a stabilized chlorine, which means it contains cyanuric acid, protecting the chlorine from the sun. The advantage of using trichlor is that it is a slow-dissolving tablet. You’ll generally put trichlor tablets in a chlorine dispenser, and it will slowly release over time. This means you won’t need to add chlorine to your pool often. In fact, you can probably get away with adding more tablets in the dispenser just once a week – or as needed.


Also available as tablets but more commonly available in granular form, dichlor is another stabilized chlorine. Dichlor is another type of chlorine that is used as pool shock. So, you won’t be using this type of chlorine very often. Since chlorine and cyanuric acid dissolve very quickly, I recommend liquid chlorine or cal hypo over dichlor when shocking your pool. But if you do use dichlor, you wouldn’t need it any more often than once a week.

As a top tip, only use dichlor if both your chlorine and cyanuric acid levels are low.

How Much Chlorine to Add to Your Pool

So, now that you know exactly how often you should add chlorine to your pool, I’ll go ahead and answer how much chlorine to add. Luckily, this is where my pool chlorine calculator comes in handy––no need to do any fancy calculations on your end!

All you need to know is your current pool chlorine level, which you can easily find out with a test kit or test strip, and your pool volume. If you’re not sure about your pool size, check out my pool volume calculator.

Then, simply plug in the numbers and the type of chlorine you’re using, and voila! You’ll know how much chlorine to add to get your chlorine levels back to 1 to 3 ppm.

Is There Such a Thing as Too Much Chlorine?

While chlorine is amazing and keeping your pool clean, yes, there is a thing as too much chlorine. There may come a time when you might go overboard in adding the chlorine to your pool, perhaps due to a slight miscalculation or a slip of the wrist. Whatever the reason, having too much chlorine, just like having too little chlorine, is not ideal. Too much chlorine in the pool can actually be harmful to swimmers, causing respiratory distress and irritation to eyes or nasal passages.

Fortunately, lowering chlorine levels is not too difficult. There are a few different methods to lower chlorine levels, including:

  • Let the sun naturally dissipate the chlorine
  • Drain and dilute the pool water
  • Use a chlorine neutralizer like sodium thiosulfate
  • Use hydrogen peroxide or ascorbic acid

How to Maintain the Chlorine Levels in Your Pool

Maintaining and balancing the chlorine levels in your pool can be tricky. Here are my top tips on how to maintain the right levels of chlorine in your pool.

Test Regularly

The most important thing you can do to maintain the chlorine levels is to test the water daily! The ideal chlorine level for pools is 1-3 ppm. Test to make sure the chlorine hovers between this range. And if it isn’t, add more chlorine!

Shock the Pool

Shocking is when you add a very high dose of chlorine to the water to eradicate algae growth or large amounts of bacteria present in the pool. This maintains chlorine levels during hot weather and busy pool seasons. Ideally, you should be shocking the pool at least once a week.

Run the Pool Pump

Running the pump every day for at least 8 hours a day is essential for a healthy pool ecosystem and good water circulation. This also helps distribute chlorine evenly throughout the pool, maintaining healthy levels.

Use a Chlorine Stabilizer

If you do not use stabilized chlorine, add cyanuric acid to your pool. Ideal CYA levels are between 30 and 50 ppm. As mentioned, CYA acts as a form of sunscreen for the water and helps preserve the chlorine levels in the water.

Keep the Pool Clean

A large part of a healthy pool system is all about balance. Chlorine keeps the pool clean, but it’s also vital to help it out by vacuuming it and removing debris so that the chlorine can function as effectively as possible.

How to Add Chlorine to Your Pool

Unsure about the right way to add chlorine to your pool? First things first, you’ll have to determine the right dosage by testing your current chlorine levels. Once you know exactly how much of the chlorine to add, the method of adding the chlorine depends on the type of chlorine you are using:

  • If you are using chlorine granules, pre-dissolve them in a 5-gallon bucket of water, then pour the solution while walking around the perimeter of the pool.
  • If using chlorine tablets, pop them into the automatic or floating chlorinator; they will then release the chlorine into the water gradually.
  • If using liquid chlorine, simply pour it into the pool on the deepest end of your pool, away from any ladders or other obstacles.

Then, start your pool pump and filter. Run it for at least 4 to 6 hours to distribute the chlorine evenly throughout the water.

Once it’s been a few hours, test the pool’s chlorine levels once again. Are the chlorine levels between 1 and 3 ppm? If yes, you’re all sorted! If not, adjust as necessary.

Get My Free Pool Care Checklist

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Frequently Asked Questions

How long does chlorine last in a pool?

How long chlorine lasts in a pool depends on several factors. Sunlight exposure, how often the pool is used, and the type of chlorine used can all affect chlorine lifespan. But chlorine can generally last between a few hours to several days.

Should I add chlorine to my pool every day?

Most types of chlorine do need to be added to your pool every day or every two days. But with that said, every pool is different, and the best way to know when you need to add chlorine to it is by testing it. It’s quick, easy, and takes only a few minutes!

How often should you add chlorine tablets to your pool?

Chlorine tablets dissolve super slowly. You might have to add fresh tablets to the chlorinator every 4 to 7 days.

Keep the Chlorine Levels Between 1 to 3 ppm!

By now, you should be a pro at knowing how often and when to add chlorine to your pool! It’s as simple as checking your levels and then topping up if necessary. Maintaining consistent chlorine levels can be a breeze, and you’ll be a proud owner of an always-sparkling pool in no time.

If you still have any questions about chlorine or other pool chemistry basics, please get in touch! I’m happy to answer any questions you may have.

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